Drawbench gripping mechanism



Aug. 28, 1962 LJ.HUMMEL DRAWBENCH GRIPPING MECHANISM Filed Feb. 11, 1960 Fig.2

2 Sheets-Sheet 1 HO H08 HO Fig.5

United States Patent 3,051,301 DRAW/BENCH GREPPRIG NEfiZHANlSM Lynn J. Hummel, Albany, N.Y., assignor to Allegheny Ludlum Steel Corporation, Brackenridge, Pa., a corporation of Pennsylvania Filed Feb. 11, 1960, Ser. No. 8,051 6 Claims. (Ql. 265-24) This invention relates generally to drawbenches and in particular to drawbench carriages for use in the drawing of tubing.

In the drawing of tubing a movable carriage having gripping means is usually utilized -to effectively grip and draw the tubing through a die. In effecting the drawing operation, the known gripping mechanisms impart de formation to the end of the tube to the extent that it is sometimes diflicult to effect a disengagement of the grippers from the tube. Further, the tip of the tube is usually so deformed that it is not possible to utilize such tip in efiecting a further drawing operation of the tubing, thus adding greatly to the cost of drawing the tubing where new gripping tips have to be formed thereon.

An object of this invention is to provide drawbench carriage with a grip mechanism that prevents excessive deformation of the tip of the tube being drawn while providing for a quick release of the drawn tube upon completion of a drawing operation.

Another object of this invention is to provide a drawbench carriage having a plug mechanism movable with and and cooperating with the gripping mechanism for holding the tip of tubing while the drawing operation is performed thereon and quickly releasing the tube upon completion of the drawing operation.

A further object of this invention is to provide a drawbench carriage having slidable gripper jaw members with a slidable block carrying a plug thereon with the block being disposed to be actuated simultaneously with the gripper jaw members to drive the plug into and out of engagement with the tubing being drawn simultaneously with the action of the gripper jaw members and a stop member associated with the plug to cooperate therewith to effectively strip the tubing from the plug upon completion of the drawing operation.

Other objects of this invention will become apparent from the following description when taken in conjunction with the following drawings in which:

FIGURE 1 is a top plan view of the layout of a drawbench for drawing tubing;

2 is a top plan view of a portion of the drawbench carriage;

FIG. 3 is an end plan view of the portion of the carriage illustrated in FIG. 2;

FIG. 4 is a top plan view of a portion of the carriage with the actuating mechanism superstructure removed therefrom and which illustrates features of this invention; FIG. 5 is a top plan view, greatly enlarged, of a stop member utilized in the assembly of FIG. 4;

FIG. 6 is a front plan view of the stop member of FIG. 5;

FIG. 7 is a side plan view of a stop member of FIGS. 5 and 6;

FIG. 8 is a view in side elevation and in section of the carriage assembly of FIGS. 1, 2 and 3 with the gripping mechanism illustrated in a gripping position for effecting the drawing of a tube through a die, and

FIG. 9 is a view in side elevation and in section similar to FIG. 8 but with the gripping mechanism illustrated in a releasing position with respect to the tubing upon completion of a drawing operation.

Referring to the drawing, and in particular to FIG. 1, this invention is illustrated as embodied in a drawbench assembly shown generally at 10, such drawbench assembly comprising a drawbench carriage 12 disposed to ride on a pair of rails 14 and to be actuated by a pair of continuous chain drives 16, the carriage having hooks (not shown) for engaging the chains 16 which are driven by a power unit represented at 18. The drawbench carriage 12 is disposed for engaging the tip of tubing 26 to draw the tubing through a die block 22. The drawbench assembly referred to and illustrated generally in FIG. 1 is a standard drawbench that may be obtained from many different sources but without the features of this invention thereon. Suitable drawbench assemblies are available from The Aetna-Standard Engineering Company of Pittsburgh, Pennsylvania.

The drawbench carriage 12. is shown in detailed plan in FIGS. 2, 3 and 4 so as to illustrate the application of the features of this invention thereto. Reference :may also be had to the sectional view shown in FIGS. 8 and 9 for clarification of certain portions of the plan outline drawings illustrated in FIGS. 2, 3 and 4. As illustrated, the trolley or carriage block 24 of the drawbench carriage 12 is provided with a pair of guide grooves 26 and Z8 disposed in the base portion thereof for receiving slidable gripper jaw members 34? and 32, respectively, the ends of the gripper jaw members being serrated as at 34 (shown in FIGS. 8 and 9) for effectively gripping the tip of the tube 2%. Mounted above the trolley or carriage block 24 is a support housing 36 for suitably supporting actuating mechanism for the gripper jaw members 30 and 32. The support housing 36 is carried on a plate 38 which is disposed across the trolley plate 24 and secured thereto above the gripper jaw members 30 and 32 as by welding (not shown). The supporting housing 36 carries a rectangular housing 40, preferably welded in place, for supporting a spring assembly 42, the purpose of which will be explained more full hereinafter. The upper edge of the housing 36 is slotted as at 44-, 46 and 48, and is provided with side plates 50 and 52, the side plates 50 and 52 also functioning to support the actuating mechanism to be referred to hereinafter. Mounted within the slots 44, 46 and 48 are three rearwardly projecting arms 54, 56 and 58, respectively, such arms being supported in assembled relation as by means of shafts of 62 and 64 extending through and supported in the side plates 50 and 52. An air cylinder 66 depends downwardly from a cross bar 68 which is secured at its ends to the side plates 50 and 52. The air cylinder 66 is preferably aligned with spring assembly 42 for cooperating therewith in controlling movement of the arm as will be explained more fully hereinafter.

In accordance with this invention, the trolley block 24 is further grooved as at 70 between the grooves 26 and 28 which carry the gripper jaw members so as to slidably receiver a plug block 72 disposed to carry a tapered plug 74 on the face thereof. This assembly is better illustrated in the sectional views of FIGS. 8 and 9. The tapered plug 74 is provided with a threaded projecting end 76 disposed in a supported engagement in a threaded opening in the block 72, the tapered block being of a predetermined size for fitting within the tip of the tube 29 that is to be drawn through the die block 22. The plug block 72 is provided on its upper surface with a groove 78 for receiving the lower end of an actuating arm 80 disposed to extend upwardly between the spring assembly 42 and the air cylinder 66 and which is fixedly mounted between the fixed side plates 59 and 52. Each of the gripper members 30 and 32 is provided with a groove 78 similar to the groove in the block 72, it being noted that the actuating arm Stl has a width sufficient to extend across the gripper jaw members and the plug block 72 so as to effect a simultaneous drive of the gripper jaw members and the block 72 in response to the actuation of either the spring assembly 3 42 or the air cylinder 66, it being further noted that the trolley block 24 is grooved as at 82 (see FIGS. 4, 8 and 9) to permit movement of the actuating arm 80 to drive the gripper jaw members and the plug block.

Referring in particular to FIGS. 8 and 9, the spring assembly 42 is provided with a fixed base plate 84 having a vent 86 therein and a movable end cap 83 disposed to seat against the actuating arm 80, a spring 96 being disposed between the fixed end plate 34 and the slidable movable end cap 88. Disposed on the other side of the actuating arm 80 is the air cylinder 66 which, in essence, is provided with a cylindrical housing 22, a movable contact piston 94 disposed to be driven to seat against the actuating arm 80, a threaded opening 96 being provided for supplying a suitable fluid supply of pressure for driving the piston head 94 to effect operation of the arm 84 or for releasing the pressure from the cylinder.

In order to efiectively strip the tube 21 from the end of the threaded plug 74 upon completion of a drawing operation, a tube stop or stripper plate 98 is disposed in cooperative relation with respect to the block 72 and is mounted on the fixed portion of the trolley block as by means of spaced screws 100. Referring to FIGS. 5, 6 and 7, the tube stop or stripper plate 93 is illustrated in greater detail, such plate 98 having an opening 102 provided therein through which the tapered plug 74 is disposed to be actuated and being of a size smaller than the external diameter of the end of the tube which is to be removed from the tapered plug 74. The plate 98 is usually made of tool steel so as to withstand impact, as will be described hereinafter, and is provided with tapered sides 104 and 196 so as to provide clearance for movement of the gripper jaw members 30 and 32, respectively, the plate also being provided with an upwardly extending flange 103 having a pair of spaced openings 110 therein for receiving screws 1% which are disposed to seat in cooperating threaded openings in the fixed portion of the trolley block 24, the back outer edges of the stopper plate 98 being flush with such fixed portion of the trolley plate so as to provide an adequate support for the stop plate 98.

While the plug 74 has been referred to as a tapered plug, it will be appreciated that the taper does not extend throughout the length of the plug since the plug in its forward movement into the tip of the tube is partially enclosed within the confines of the opening 162 in the stop plate 98. As a typical example of the tapered plug 74, such plug may have an over-all length of 7% inches including the threaded tip 76 which, of itself, is 1% inches in length, the base of the plug 74 seating against the plug block 72 having a 2-inch diameter, which diameter extends a distance of 2% inches longitudinal of the plug, the plug thereafter being provided with a 1 taper and terminating in a spherical radius. Where the untapered portion of the plug 74 has a diameter of 2 inches, the opening 102 in the stop plate 98 is provided with an inner diameter of 2.062 inches to provide clearance for free movement of the plug through the opening 1G2. It will be appreciated the foregoing example is illustrated only since the size of the plug and the opening therefor will vary depending on the size of the tubing to be drawn.

In practice the carriage 12 is moved to a forward position toward the die block 22 to a position where the tapered plug carried by block 72 makes entry of the tube tip of the tube 20, and gripper jaw members 30 and 32 are simultaneously actuated toward the tube under the influence of the action of the air cylinder 66 when fluid pressure is admitted thereto to drive the arm 80 in a clockwise direction as shown in FIGS. 8 and 9. It is to be noted that such operation of the arm 80 which is in contact with the end cap 88 of the spring assembly 42 also compresses the spring 90. The simultaneous action of the members 74, 30 and 32 effectively drives the tapered plug into the tip of the tube 20 and simultaneously actuates the gripper jaw members into a gripping position about the outer periphery of the tube tip so as to effectively hold the tube tip in position on the tapered plug '74 without detrimenal deformation of such tip.

As soon as the tube tip is gripped as described, hooks (not shown) secured to the carriage 12 are dropped into the continuously driven chains 16 to efiect movement of the carriage 12 away from the die block 22 to draw the tube 2t} through the die contained therein. As soon as movement of the carriage 12 is started, the fluid pressure to the cylinder 66 is released, but since the carriage is moving away from the die block 22, the wedging action of the gripper jaws on the tube tip (caused by the tension in the tube) maintains the grip on the tip of the tube to hold the tube securely in position on the tapered plug 74. This tension in the tube is maintained throughout the drawing operation with the result that the gripper jaw members cooperate with the tapered plug 74 to hold the tube tip in a gripping relation until the tube is effectively drawn and clears the die plug 22.

As soon as the tube 2% clears the die block 22, the kinetic energy created by the tension developed as the tube is being drawn causes the tube to substantially leap from the die block 22 toward the carriage with the result that the wedging action of the gripper jaw members is released, the spring of the spring assembly 42 functions to drive the end cap 88 against the actuating arm 86 to effect a counter-clockwise movement thereof to simultaneously drive the block 72 carrying the tapered plug 74 and the gripper jaw members 30 and 32 in a direction away from the tube while at the same time the end of the tube tip strikes the stop plate 98 and rebounds therefrom, falling out of the carriage. When the tube tip is thus held and released through the cooperative efiorts of the gripper jaw members 30- and 32 and the tapered plug 74, it is found that the tapered plug serves to keep the tube tip from collapsing due to the gripping pressure, thereby removing the necessity of having to reshape the tube tip for further redrawing operations, and with the stripping action described, prevents the tube from hanging up in the drawbench carriage.

The apparatus of this invention is quite efiective for holding a tube tip during a drawing operation without imparting thereto any detrimental deformation while utilizing the kinetic energy developed by the tension imparted during the drawing operation to effect stripping of the tube from the tapered plug. From the description given hereinbefore, it is quite apparent that the gripper jaw members and tapered plug cooperate for the purpose described, such members being simultaneously actuated into engagement with the tube tip and being maintained in a gripping relation during the entire drawing operation while effecting simultaneous release of the tube tip under the driving force of the tube as the tension of the tube is released when the tube becomes free from the die, the stripper plate effectively cooperating with the tapered plug to effect a stripping operation without interfering with the movement of the tapered plug therein.

The present invention isv adaptable to any of the conventional drawbench carriages to enhance the utility thereof and make it possible to effectively draw tubing without damaging the tube tip. As will be apparent, the modification in existing drawbench carriages necessary to employ the present invention can be readily performed so that, with the present teachings, one skilled in the art can readily reproduce the present invention.

I claim:

1. In a drawbench carriage having slidable gripper jaw members disposed to be actuated to engage and hold the end of a tube during a drawing operation, a pivoted arm disposed to engage and to be operated to simultaneously actuate said gripper jaw members into and out of said holding engagement, actuating means disposed to be operated to drive the pivoted arm in a direction to actuate the gripper jaw members into said holding engagement, and actuating means disposed to drive the pivoted arm in the opposite direction to actuate the gripper jaw members away from said holding engagement, the combination therewith of, a block disposed for slidable movement between said gripper jaw members, a tapered plug carried by the block, the tapered plug being disposed to extend forward therefrom centrally of the gripper jaw members and in alignment with the end of the tube, said plug being of a size to fit into said tube, the block having means disposed in engagement with the pivoted arm to be actuated thereby simultaneously with the actuation of the gripper jaw members whereby the plug is moved into the end of the tube as the gripper jaw members are driven into engagement therewith and the plug is driven in a direction away from the tube as the gripper jaw members are released therefrom, the plug cooperating with the jaw members when the jaw members grip the tube to prevent collapse of the end of the tube under the gripping force of the jaw members, and tube stop means disposed closely adjacent the tapered plug without interfering with the movement thereof for receiving the end of the tube when the gripper jaws are released therefrom to facilitate stripping the tube from the tapered plug as the plug moves away from the tube.

2. In a drawbench carriage having slidable gripper jaw members disposed to be actuated to engage and hold the end of a tube during a drawing operation, a pivoted arm in engagement with the gripper jaw members and disposed to be operated to simultaneously actuate said gripper jaw members into and out of said holding engagement, actuating means disposed to be operated to drive the pivoted arm in a direction to actuate the gripper jaw members into said holding engagement, and actuating means disposed to drive the pivoted arm in the opposite direction to actuate the gripper jaw members away from said holding engagement, the combination therewith of, a block disposed for slidable movement between said gripper jaw members, an elongated plug carried by the block, the plug being disposed to extend forward therefrom centrally of the gripper jaw members and in alignment with the end of the tube, said plug being of a size to fit into and support said tube, the block being disposed to be engaged by the pivoted arm to be actuated thereby simultaneously with the actuation of the gripper jaw members to drive the plug into the end of the tube as the gripper jaw members are driven into engagement therewith and to tend to drive the plug in a direction away from the tube as the gripper jaw members are released therefrom, the plug cooperating with the jaw members when the jaw members grip the tube to prevent the collapse of the end of the tube under the gripping force of the jaw members, and means carried by the carriage and disposed about the plug for receiving the end of the tube when the gripper jaw means are released therefrom and the plug tends to move away from the tube to facilitate stripping the tube from the plug.

3. In a drawbench carriage having slidable gripper jaw members disposed to be actuated to engage and hold the end of a tube during a drawing operation, a pivoted arm in engagement with the gripper jaw members and disposed to be operated to simultaneously actuate said gripper jaw members into and out of said holding engagement, actuating means disposed to be operated to drive the pivoted arm in a direction to actuate the gripper jaw members into said holding engagement, and actuating means disposed to drive the pivoted arm in the opposite direction to actuate the gripper jaw members away from said holding engagement, the combination therewith of, a block disposed for slidable movement between said gripper jaw members, a tapered plug canied by the block, the tapered plug being disposed to extend forward therefrom centrally of the gripper jaw members and in alignment with the end of the tube, said plug being a size to fit into said tube, the block being disposed to be engaged by the pivoted arm to be actuated thereby simultaneously with the actuation of the gripper jaw members to drive the plug into the end of the tube as the gripper jaw members are driven into engagement therewith and to tend to drive the plug in a direction away from the tube as the gripper jaw members are released therefrom, the plug cooperating with the jaw members when the jaw members grip the tube to prevent collapse of the end of the tube under the gripping force of the jaw members, and means carried by the carriage and disposed about the plug for receiving the end of the tube when the gripper jaw means are released therefrom and the plug tends to move away from the tube to facilitate stripping the tube from the plug.

4. In a drawbench carriage having slidable gripper jaw members disposed to be actuated to engage and hold the end of a tube during a drawing operation, a pivoted arm in engagement with the gripper jaw members and disposed to be operated to simultaneously actuate said gripper jaw members into and out of said holding engagement, actuating means disposed to be operated to drive the pivoted arm in a direction to actuate the gripper jaw members into said holding engagement, and actuating means disposed to drive the pivoted arm in the opposite direction to actuate the gripper jaw members away from said holding engagement, the combination therewith of, a block disposed for slidable movement between said gripper jaw members, an elongated plug carried by the block, the plug being disposed to extend forward therefrom centrally of the gripper jaw members and in alignment with the end of the tube, said plug being of a size to fit into and support said tube, the block being disposed to be engaged by the pivoted arm to be actuated thereby simultaneously with the actuation of the gripper jaw members to drive the plug into the end of the tube as the gripper jaw members are driven into engagement therewith and to tend to drive the plug in a direction away from the tube as the gripper jaw members are released therefrom, the plug cooperating with the jaw members when the jaw members grip the tube to prevent collapse of the end of the tube under the gripping force of the jaw members, and tube stop means carried by the carriage and disposed closely adjacent the plug without interfering with the movement thereof for receiving the end of the tube when the gripper jaw members are released therefrom to facilitate stripping the tube from the plug as the plug moves away from the tube.

5. In a drawbench carriage having slidable gripper jaw members disposed to be actuated to engage and hold the end of a tube during a drawing operation, a pivoted arm in engagement with the gripper jaw members and disposed to be operated to simultaneously actuate said gripper jaw members into and out of said holding engagement, actuating means disposed to be operated to drive the pivoted arm in a direction to actuate the gripper jaw members into said holding engagement, and actuating means disposed to drive the pivoted arm in the opposite direction to actuate the gripper jaw members away from said holding engagement, the combination therewith of, a block disposed for slidable movement between said gripper jaw members, a tapered plug carried by the block, the tapered plug being disposed to extend forward therefrom centrally of the gripper jaw members and in alignment with the end of the tube, said plug being of a size to fit into and support said tube, the block being disposed to be engaged by the pivoted arm to be actuated thereby simultaneously with the actuation of the gripper jaw members to drive the plug into the end of the tube as the gripper jaw members are driven into engagement therewith and to tend to drive the plug in a direction away from the tube as the gripper jaw members are released therefrom, the plug cooperating with the jaw members when the jaw members grip the tube to prevent collapse of the end of the tube under the grip ping force of the jaw members, and tube stop means carried by the carriage and disposed closely about the plug without interfering with the movement thereof for receiving the end of the tube when the gripper jaw mem- 6. In a drawbench carriage having slidable gripper jawv members disposed to be actuated to engage and hold the end of a tube during a drawing operation, a pivoted arm in engagement with the gripper jaw members and disposed to be operated to simultaneously actuate said gripper jaw members into and out of said holding engagement, actuating means disposed to be operated to drive the pivoted arm in a direction to actuate the gripper jaw members into said holding engagement, and actuating means disposed to drive the pivoted arm in the opposite direction to actuate the gripper jaw members away from said holding engagement, the combination therewith of, a block disposed for slidable movement between said gripper jaw members, a tapered plug carried by the block, the tapered plug being disposed to extend forward therefrom centrally of the gripper jaw members and in alignment with the end of the tube, said plug being of a size to fit into and support said tube, the block being disposed to be engaged by the pivoted arm to be actuated thereby simultaneously with the actuation of the gripper jaw members to drive the plug into the end of the tube as the gripper jaw members are driven into engagement therewith and to tend to drive the plug in a direction away from the tube as the gripper jaw members are released therefrom, the plug cooperating with the jaw members when the jaw members grip the tube to prevent collapse of the end of the tube under the gripping force of the jaw members, and tube stop means disposed between the gripper jaw members in the path of movement of the tapered plug and the tube thereon, the stop means having an opening therein of a size to receive and permit movement of the tapered plug therein but to prevent entry of the tube therein, said stop means thereby eifectively stopping movement of the tube in the direction of movement of the plug when the gripper jaw members are released to thereby facilitate stripping the tube from the tapered plug.

References Cited in the file of this patent UNITED STATES PATENTS 

